1. Field of the Invention
The present invention relates to an image recording apparatus, and an apparatus, method and a recording medium for optimizing a defective-recording-element compensation parameter, and particularly, relates to a correction technique for a defective recording element including a non-discharge nozzle in an image recording apparatus such as an ink-jet recording apparatus.
2. Description of the Related Art
In the image recording by the ink-jet method, a nozzle in a non-discharge state (non-discharge nozzle) is produced by a clogging or a malfunction in association with use of an ink-jet head. In the case of the image recording by the single pass method, a white line is recognized at the position for the non-discharge nozzle in an image, and therefore, a correction (compensation) is necessary. To date, many correction techniques for the non-discharge nozzle have been proposed.
When the white line caused by the production of the non-discharge nozzle appears, the image recording by non-discharge correction nozzles, which are normal nozzles close to the non-discharge nozzle, is deepened, and thereby, the visibility of the white line is decreased. Examples of the method for deepening the image recording by the non-discharge correction nozzles include a method of scanning an output image, a method of intensifying a discharge signal and rectifying the discharge dot diameter such that it is increased, and the like.
A non-discharge correction parameter indicating the correction intensity in the non-discharge correction nozzle depends on the degree of the variability among nozzles in the impact position errors of the ink to be discharged from the nozzles, and the degree of the variability in the amount of the ink to be discharged from the nozzles, and therefore, the optimum values are different values for each nozzle.
However, the number of nozzles in an ink-jet head to perform the image recording by the single pass method, which is several thousands to several tens of thousands, is very high, and it is required that a technique for optimizing all these many nozzles has an efficient optimizing scheme.
Japanese Patent Application Laid-Open No. 2012-71474 describes a correction technique for a defective recording element that utilizes a defective-recording-element compensation parameter selection chart. The defective-recording-element compensation parameter selection chart is configured by a reference patch and a measurement patch. The reference patch is configured by a uniform image that has a constant gradation and a uniform concentration and in which a region on a recorded medium is drawn.
In the measurement patch, one or plural of a plurality of recording elements to draw the reference patch is in a non-recording state, and a candidate value of a defective-recording-element compensation parameter indicating a correction amount is given at the drawn part by a recording element to perform the recording near the non-recording position for the recording element of the non-recording. Further, the measurement patch reproduces a state after the correction by the correction amount corresponding to the candidate value of the defective-recording-element compensation parameter.
Then, the defective-recording-element compensation parameter selection chart is read by an optical reading apparatus. In the calculation of an evaluation value that is an evaluation index for evaluating the difference between a capture image for the reference patch and a capture image for the measurement patch, a weight reflecting the recording property of a recording head for recording the reference patch is given to a value indicating the difference between the capture image for the reference patch and the capture image for the measurement patch, and the evaluation value is calculated. Then, the defective-recording-element compensation parameter is calculated based on the evaluation value.
The correction technique described in Japanese Patent Application Laid-Open No. 2012-71474 can efficiently select the defective-recording-element compensation parameter, in the case of targeting only particular recording elements.